traefik/vendor/github.com/go-acme/lego/providers/dns/rfc2136/rfc2136.go
2019-03-14 11:04:04 +01:00

183 lines
6 KiB
Go

// Package rfc2136 implements a DNS provider for solving the DNS-01 challenge using the rfc2136 dynamic update.
package rfc2136
import (
"errors"
"fmt"
"net"
"strings"
"time"
"github.com/go-acme/lego/challenge/dns01"
"github.com/go-acme/lego/platform/config/env"
"github.com/miekg/dns"
)
// Config is used to configure the creation of the DNSProvider
type Config struct {
Nameserver string
TSIGAlgorithm string
TSIGKey string
TSIGSecret string
PropagationTimeout time.Duration
PollingInterval time.Duration
TTL int
SequenceInterval time.Duration
DNSTimeout time.Duration
}
// NewDefaultConfig returns a default configuration for the DNSProvider
func NewDefaultConfig() *Config {
return &Config{
TSIGAlgorithm: env.GetOrDefaultString("RFC2136_TSIG_ALGORITHM", dns.HmacMD5),
TTL: env.GetOrDefaultInt("RFC2136_TTL", dns01.DefaultTTL),
PropagationTimeout: env.GetOrDefaultSecond("RFC2136_PROPAGATION_TIMEOUT", env.GetOrDefaultSecond("RFC2136_TIMEOUT", 60*time.Second)),
PollingInterval: env.GetOrDefaultSecond("RFC2136_POLLING_INTERVAL", 2*time.Second),
SequenceInterval: env.GetOrDefaultSecond("RFC2136_SEQUENCE_INTERVAL", dns01.DefaultPropagationTimeout),
DNSTimeout: env.GetOrDefaultSecond("RFC2136_DNS_TIMEOUT", 10*time.Second),
}
}
// DNSProvider is an implementation of the acme.ChallengeProvider interface that
// uses dynamic DNS updates (RFC 2136) to create TXT records on a nameserver.
type DNSProvider struct {
config *Config
}
// NewDNSProvider returns a DNSProvider instance configured for rfc2136
// dynamic update. Configured with environment variables:
// RFC2136_NAMESERVER: Network address in the form "host" or "host:port".
// RFC2136_TSIG_ALGORITHM: Defaults to hmac-md5.sig-alg.reg.int. (HMAC-MD5).
// See https://github.com/miekg/dns/blob/master/tsig.go for supported values.
// RFC2136_TSIG_KEY: Name of the secret key as defined in DNS server configuration.
// RFC2136_TSIG_SECRET: Secret key payload.
// RFC2136_PROPAGATION_TIMEOUT: DNS propagation timeout in time.ParseDuration format. (60s)
// To disable TSIG authentication, leave the RFC2136_TSIG* variables unset.
func NewDNSProvider() (*DNSProvider, error) {
values, err := env.Get("RFC2136_NAMESERVER")
if err != nil {
return nil, fmt.Errorf("rfc2136: %v", err)
}
config := NewDefaultConfig()
config.Nameserver = values["RFC2136_NAMESERVER"]
config.TSIGKey = env.GetOrFile("RFC2136_TSIG_KEY")
config.TSIGSecret = env.GetOrFile("RFC2136_TSIG_SECRET")
return NewDNSProviderConfig(config)
}
// NewDNSProviderConfig return a DNSProvider instance configured for rfc2136.
func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
if config == nil {
return nil, errors.New("rfc2136: the configuration of the DNS provider is nil")
}
if config.Nameserver == "" {
return nil, fmt.Errorf("rfc2136: nameserver missing")
}
if config.TSIGAlgorithm == "" {
config.TSIGAlgorithm = dns.HmacMD5
}
// Append the default DNS port if none is specified.
if _, _, err := net.SplitHostPort(config.Nameserver); err != nil {
if strings.Contains(err.Error(), "missing port") {
config.Nameserver = net.JoinHostPort(config.Nameserver, "53")
} else {
return nil, fmt.Errorf("rfc2136: %v", err)
}
}
if len(config.TSIGKey) == 0 && len(config.TSIGSecret) > 0 ||
len(config.TSIGKey) > 0 && len(config.TSIGSecret) == 0 {
config.TSIGKey = ""
config.TSIGSecret = ""
}
return &DNSProvider{config: config}, nil
}
// Timeout returns the timeout and interval to use when checking for DNS propagation.
// Adjusting here to cope with spikes in propagation times.
func (d *DNSProvider) Timeout() (timeout, interval time.Duration) {
return d.config.PropagationTimeout, d.config.PollingInterval
}
// Sequential All DNS challenges for this provider will be resolved sequentially.
// Returns the interval between each iteration.
func (d *DNSProvider) Sequential() time.Duration {
return d.config.SequenceInterval
}
// Present creates a TXT record using the specified parameters
func (d *DNSProvider) Present(domain, token, keyAuth string) error {
fqdn, value := dns01.GetRecord(domain, keyAuth)
err := d.changeRecord("INSERT", fqdn, value, d.config.TTL)
if err != nil {
return fmt.Errorf("rfc2136: failed to insert: %v", err)
}
return nil
}
// CleanUp removes the TXT record matching the specified parameters
func (d *DNSProvider) CleanUp(domain, token, keyAuth string) error {
fqdn, value := dns01.GetRecord(domain, keyAuth)
err := d.changeRecord("REMOVE", fqdn, value, d.config.TTL)
if err != nil {
return fmt.Errorf("rfc2136: failed to remove: %v", err)
}
return nil
}
func (d *DNSProvider) changeRecord(action, fqdn, value string, ttl int) error {
// Find the zone for the given fqdn
zone, err := dns01.FindZoneByFqdnCustom(fqdn, []string{d.config.Nameserver})
if err != nil {
return err
}
// Create RR
rr := new(dns.TXT)
rr.Hdr = dns.RR_Header{Name: fqdn, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: uint32(ttl)}
rr.Txt = []string{value}
rrs := []dns.RR{rr}
// Create dynamic update packet
m := new(dns.Msg)
m.SetUpdate(zone)
switch action {
case "INSERT":
// Always remove old challenge left over from who knows what.
m.RemoveRRset(rrs)
m.Insert(rrs)
case "REMOVE":
m.Remove(rrs)
default:
return fmt.Errorf("unexpected action: %s", action)
}
// Setup client
c := &dns.Client{Timeout: d.config.DNSTimeout}
c.SingleInflight = true
// TSIG authentication / msg signing
if len(d.config.TSIGKey) > 0 && len(d.config.TSIGSecret) > 0 {
m.SetTsig(dns.Fqdn(d.config.TSIGKey), d.config.TSIGAlgorithm, 300, time.Now().Unix())
c.TsigSecret = map[string]string{dns.Fqdn(d.config.TSIGKey): d.config.TSIGSecret}
}
// Send the query
reply, _, err := c.Exchange(m, d.config.Nameserver)
if err != nil {
return fmt.Errorf("DNS update failed: %v", err)
}
if reply != nil && reply.Rcode != dns.RcodeSuccess {
return fmt.Errorf("DNS update failed: server replied: %s", dns.RcodeToString[reply.Rcode])
}
return nil
}